Compressor unloading mechanism



1941. H. A. GEHRES 2,241,195

COMPRESSOR UNLOADING MEGHANI SM Filed Jan. 10, .1939 5 Sheets-Sheet 1 y 6, 1941- H. A. GEHRES 2,241,195

COMPRESSOR UNLOADING MECHANISM Filed Jan. 10, 1939 3 Sheets- Sheet 2 INVENTOR WXW M tr-Lamp ATTOR EYS y 1941. H. A. GEHRES 2,241,195

COMPRESSOR UNLOADING MECHANISM Filed Jan. 10, 1959 3 Sheets-Sheet 3 INVENTOR /M 42 W BY M M v hmQ ATTO R N EYS Patented May 6, 1941 2,241,195 I comanssoa momma MECHANISM Hewitt A. Gehres, Mount Vernon, Ohio, as-

signor to Cooper-Bessemer Corporation, Mount Vernon, Ohio, a corporation of Ohio Application January 10, 1939, Serial No. 250,093

3 Claims.

Compressor unloading mechanisms have been long known wherein a valve was employed to open communication between the cylinder space and a clearance chamber or otherwise relieve the pressure in the cylinder when it was desired to have the compressor operate at less than full capacity. The present invention has to do with devices of 'the above character and aims in one of its aspects to provide a compressor unloading mechanism so combined with the ordinary suction or discharge valve constructions as to enable unloading steps to be carried out without requiring special or awkward modification of the cylinder construction. In accordance with the invention many different unloading stages may be obtainedin a simple way. Further objects and advantages of the invention willbeinpart obvious and in part2 specifically referred to in the description hereinafter contained which, taken in conjunction with the accompanying drawings, discloses the invention as applied to unloading mechanism of certain specific constructions; from, the standpoint of the invention in its broader aspects however the disclosure should be considered as merely illustrative of the principles of the invention. In the drawings- Fig. 1 is a central longitudinal section taken through an unloading mechanism construc Y to operate in accordance with the invention, and shown in operative position with respect to adjacent parts of a compressor cylinder.

Fig. 2 is a bottom plan view of the mechanism shown in Fig. 1.

Fig. 3 is a central longitudinal section showing a compressor cylinder equipped with several specific forms of unloading mechanism which may be used toenable multi-step unloading to be carried out in accordance with the invention.

Figs. 4 to 8 are schematic views showing various multi-stage unloading systems operating in accordance with the invention.

In accordance with one phase of the present invention I combine with known types of compressor suction or discharge valves, or both, further valve members which form a constituent part of the valve structure but which may be operated separately from the usual suction or discharge controlling valve members, to relieve the pressure within the cylinder when it is desired to unload the compressor.

In Figs. 1 and 2 the invention is disclosed as applied to a compressor valve mechanism of the general type disclosed in U. S. Patent No. 1,890,- 051 issued to me on December 6, 1932, the valve mechanism as a whole being mounted in an opening l in a compressor cylinder wall 2, which opening communicates with the cylinder space 3 at one end of the cylinder.

The illustrated construction of Fig. 1 is of a discharge valve mechanism which includes a plate-like valve seat member 4 having a series of arcuate passageways 5 extending therethrough, and a movable annular valve member 6 interposed between valve seat 4 and an annular valve guard I, the movable valve member 6 seating against the walls which define arcuate passageways 5 when the valve is closed and moving toward the guard I when the valve is open, so as to permit the discharge of compressed gas from the cylinder space 3 through the valve into an annular passageway 8 through port 0 into a discharge conduit iii in the cylinder wall. As shown, a spacer piece I l holds the parts 4 and 1 in proper position and is in turn held in position by the valve cap I2, which latter is clamped to the cylinder wall by bolts l3 acting to compress a gasket l4 between cap I2 and spacer piece ii and a gasket l5 between valve seat 4 and an opposed shoulder .in the cylinder wall, to prevent leakage.

An unloading valve member is combined with the discharge valve structure above set forth; in the form oi/the invention under discussion, this unloading valve mechanism includes a movable poppet valve member IG having a stem l'l extending longitudinally through an unloading passageway l8, the valve member I6 when closed engaging a valve seat IS in a sleeve 20 which surrounds the unloading passageway l8 above described, and is received centrally within valve seat 4, valve guard I and spacer piece Ii. As shown a nut 2i engages between collar 20 and spacer piece It to clamp the above parts together. Thus an unloading valve construction is provided within the confines of the usual compressor valve mechanism, and which requires no additional special construction of the cylinder wall 2, beyond the recess therein which is provided to receive the discharge valve mechanism proper. The unloading mechanism therefore may be easily incorporated into existing cylinder constructions.

As shown in Fig. l, the unloading valve I6 is guided by lugs 22 on the valve seat 4 in moving between closed position and the open position shown in Fig. 1, the valve stem ll being received within a bearing 23 held in position by a spider 24. A spring 25 acting between the spider 24 and a collar 25 on valve [1, urges the valve it toward closed position, and when it is desired to unload the cylinder, valve member I is held open by suitable means. As shown in Fig. 1, a plunger 21 is mounted in valve cap I! for the above purpose, the plunger 21 being pressiu'econtrolled by a piston 23 operating in cylinder 29 having a control passageway 30 leading thereto.

In the particular form of the invention which is shown in Fig. 1, the unloading passageway l8 communicates through a passageway 3| in cap l3, with a clearance bottle 32 indicated diagrammatically in Fig. 1 as attached to .cap l2, and which will be oi such volume as is required to unload the compressor to the desired extent when valve I8 is open.

In Fig. 3 I have shown a compressor cylinder having two suction valve mechanisms and two discharge valve mechanisms, each equipped with unloading valve members operating in accordance with the present invention to enable multistage unloading of the compressor to be carried out. As shown in Fig. 3 the suction conduit 33 communicates through suction passages 34 with the suction valve mechanisms indicated generally by numerals 35 and 35 which are mounted respectively in the cylinder openings 31 and 38 at the opposite ends of the cylinder. Likewise the discharge conduit 39 is in communication through discharge passageways 40 with the discharge valve mechanisms denoted generally by numerals 4| and 42 which are respectively received within openings 43 and 44 in the opposite ends of the cylinder. The valve 4| may be taken as similar in construction and mode of operation to the one previously described in connection with Figs. 1 and 2, and is shown as controlling communication to a clearance bottle 45. The discharge valve mechanism 42 likewise controls communication to a clearance bottle 46, and is similar in construction to the valve mechanism described in connection with Fig. 1 except that the valve rod Ila (Fig. 3) is opened by means of a manually operated screw-threaded plunger 21a having a hand wheel 41 attached thereto. The suction valve mechanism 35 may also be taken as similar to the valve mechanism shown in Fig. 1, except that the valve guard lb is'interposed between the valve seat 412 and the cylinder space, and with the further modification that the valve cap I 211 is provided with one passage 3") which leads to a clearance bottle 48, and a further passage 49 which leads to a valve 33 urged to move away from its seat by spring 81, and when open communicating through pipe I2 with the suction conduit 33. Thus when the unloading valve member lib is open, a partial unloading efl'ect will be imposed upon the corresponding end of the cylinder by the clearance bottle 48, unless or until valve 50 is unseated, in which latter event the pipe 52 bypasses gas under pressure from the cylinder space back into the suction conduit 33 to completely unload the corresponding end of the cylinder. Valve 50 may be held closed or permitted to open, by sui able means such as piston 50a operating in cylinder having a control passage 500.

The suction valve mechanism 36 is shown as somewhat modified in construction and mode or operation as compared to the one last above described, in that no clearance chamber is associated therewith, and its unloading valve when -open affords communication from the corre- Fig. 3, the sleeve Me has ports 53 therein which communicate through corresponding openings 34 in the spacer piece lie, with suction eway 34. To cooperate in aflording certain partial unloading stages, a further clearance chamber 35 may be provided in the head end of the cylinder. communication to which is controlled by a valve 58 provided with suitable mechanism such as the threaded rod 51 and hand wheel 83 sponding cylinder space back into the suction passageway 34, thus by-passing the suction valve proper and completely unloading the corresponding end of the cylinder. As shown in for adjusting the same to open or closed positions.

Valve mechanisms as above described may readily be employed to aflord a variety oi unloading sequences. In Fig, 4, for example, I have indicated diagrammatically a compressor cylinder equipped with suction valves 58 which may be taken to be or previously known construction, and discharge valves 60 which may be taken to be the same as the valve mechanism shown in Fig. 1, a valve SI (and associated parts) similar to the valve 53 being provided at the head end of the cylinder. This arrangement will afford five step unloading as follows: For full load both valves 60 and valve SI are closed; for one-quarter unloading valve BI is open, both valves 60 remaining closed; for one-half unloading valve 60 at the right hand end of the cylinder is open, the other valve 60 and valve 6| being closed; for three-quarter unloading the valve 60 at the right hand end of the cylinder and valve 6| are open, the other valve 60 remaining closed; and for full unloading both valves 60 are open.

Fig. 5 illustrates a cylinder construction involving two suction valve mechanisms similar to valve mechanism 36 previously described, and having the unloading valves 62, and also having a valve H as above described in connection with Fig. 4. For full load both valves GI and 62 are closed; for one-quarter unloading valve 6| is open, both valves 62 remaining closed; for onehalf unloading valve 62 at the right hand end of the cylinder is open, and valve 6| and the other valve 82 closed; for three-quarter unloading valve GI and the valve 62 at the right hand end of the cylinder are open, the other valve 62 being closed; and for full unloading both valves 52 are open. The discharge valves 63 of Fig. 5 may be of previously known construction.

Fig. 6 illustrates an arrangement similar to Fig. 5 except that the discharge valve mechanisms instead of the inlet valve mechanisms, are constructed to provide for the unloading. In Fig. 6 the suction valves 84 may be regarded as oi' previously known construction, the valve 6| is as previously described, and the dischargce valve mechanisms are provided with unloading valves 65 as previously described in connection with valve mechanism 36, except that a pipe 61 is provided to afiord communication between the valves 85 (constituting parts of the discharge valve mechanisms) and the suction passage of the compressor. The sequence of unloading steps in Fig. 6 is the same as described in connection with Fig. 5. In other words, valves 65 plus the pipe 61 of Fig, 6, function in the same way as the valves 62 of Fig. 5.

Fig. 7 illustrates another arrangement, the valve 6| being as previously described, and the discharge valves 68 being of any suitable or presaints space communicates with a clearance chamber II to afiord partial unloading; but when a valve 12 in Fig. 7 (similar to valve 50 of Fig. 3) is also open a by-pass is formed between the cylinder space and the suction passageway, thus fully unloading the corresponding end of the cylinder. In Fig. '7 the sequence of unloading steps is as follows: When fully loaded all of the valves ll, 69 and 10 are closed; for one-quarterunloading valve BI is open, valves 8! and 10 being closed; for one-half unloading valve Si is open and valve 10 is open to clearance chamber ll, valves 68 and I2 being closed; for three-quarter unloading valves 6|, l and are open, valve 69 being closed; for full unloading valves 69, ill and I2 are all open.

According to Fig. 8 the suction valve mechanisms at opposite ends of the compressor are provided with unloading valves 13 and I4 similar tothe valve 10 described in Fig. I, which control communication respectively to clearance chambers and 16, and also operate in con-' Junction respectively with valves l1 and II, both similar to the valve 12 in function. In Fig. 8,

for full load both valves I3 and I4 will beclosed;

for one-quarter unloading valve 13 will be open to clearance chamber 15, valve 14 and valve'll remaining closed; for one-half unloading valves 13 and I4 will be open for communication respectively to clearance chambers IS and, 16,

valves l1 and 18 remaining closed; for three quarter unloading valves I3 and I1 will be open, also valve 14, but valve 18 will be closed; ior iull unloading all of the valves 13,", I1 and 18 will be open. In Fig. 8 the discharge valves ll may be regarded as of any suitable or previously known construction. I

The number oi unloading steps which may While the invention has been disclosed as carried out by the above described specific constructions, it should be understood that many changes may be made therein without departing from the invention in its broader aspects, within the scope of the appended claims.

I claim:

1. In combination, a compressor cylinder including suction and discharge valve mechanisms having rigidly mounted valve seat members and movable valve members constructed and arranged to periodically open and close communication through said valve seat members, at least one of said valve mechanisms having therein an unloading passageway leading to the cylinder space which is additional to the parts above set forth, and an unloading valve member also additional to .the parts above mentioned, said unloading valve member provided with means tor holding the same in positions respectively opening and closing communication between the cylinder space and said last mentioned passageway, said last mentioned passageway communicatin with the suction passage of the compressor.

-2. In combination, a compressor cylinder having an unloading passageway therein, an unloading valve member provided with means for holding the same in positions respectively opening -and closing communication between the cylinder space and said unloading passageway, a clearance chamber communicating with said passageway, and a iurther valve member controlling communication between said passageway and the suction passage 01 the compressor.

3. In combination, a compressor cylinder including suction and discharge valve mechanisms having rigidly mounted valve seat members and movable valve members constructed and arranged to periodically open and close communication through said valve seat members, at least one or said valve mechanisms having therein an unloading passageway leading to the cylinder space be povided in any given installation will depend upo the number of suction and discharge valve ,meafianisms employed, and the extent to which they are all equipped with unloading valves of the character above described, as well as the particular way in which the unloading valves are which is additional to the parts above set forth, and an unloading valve member also additional to the parts above mentioned, said unloading valve member provided with means for holdin the same in positions respectively opening and closing communication between the cylinder connected. Unloading valves of the type above Y described in connection with valve mechanism II will aii'ord two unloading steps, whereas the simpler form *describedin connection with the valve mechanism 4| for example provides only one unloading step. The arrangement of Fig. 3 will provide for unloading in'a greater number 01' stages than above described.

space and said last mentioned passageway, a clearance chamber communicating with said passageway and a further valve member controlling communication between said passageway and the suction passage of the compressor.

HEWITT A. saunas. 

